The ratio of aspartate aminotransferase to alanine aminotransferase: Potential value in differentiating nonalcoholic steatohepatitis from alcoholic liver disease

OBJECTIVE: The ratio of aspartate aminotransferase (AST) to alanine aminotr ansferase (ALT) is often greater than 2:1 in alcoholic hepatitis. The purpo se of this study was to determine whether this ratio may be used to disting uish nonalcoholic steatohepatitis (NASH) from alcoholic liver disease. METHODS: Patients with NASH were matched with controls with alcoholic liver disease based on age, gender, and date of diagnosis. The diagnosis of alco holic liver disease was based on exclusion of other causes and a significan t history of alcohol consumption. The diagnosis of nonalcoholic steatohepat itis was based on exclusion of other causes of liver disease and a liver bi opsy showing >10% steatosis and inflammation. The two sided Student t test was used for statistical analysis. RESULTS: From 1990 to 1996, 70 patients with NASH were matched with 70 subj ects with alcoholic liver disease. Patients with NASH had a mean AST to ALT ratio of 0.9 (range 0.3-2.8, median 0.7) and subjects with alcoholic liver disease a mean ratio of 2.6 (range 1.1-11.2, median 2.0). The mean AST lev els were 66 U/L and 152 U/L, and the mean ALT levels 91 U/L and 70 U/L, in the nonalcoholic steatohepatitis and alcoholic liver disease groups, respec tively. Although the absolute aminotransferase levels were significantly di fferent in the two groups (p < 0.05), the greatest difference was observed in the AST to ALT ratio (p < 0.000001). Subset analysis of patients with NA SH revealed mean AST to ALT ratios of 0.7, 0.9, and 1.4 for subjects with n o fibrosis, mild fibrosis, or cirrhosis, respectively. The differences amon g these ratios were statistically significant (p < 0.05). CONCLUSIONS: The AST to ALT ratio appears to be a useful index for distingu ishing nonalcoholic steatohepatitis from alcoholic liver disease. Although values <1 suggest NASH, a ratio of greater than or equal to 2 is strongly s uggestive of alcoholic liver disease. (C) 1999 by Am. Cell. of Gastroentero logy.